In a cellular network, an outage of a network element or a cell can occur for several reasons, such as failures in the power supply, hardware or software errors. The problem related to outages of a cell in a cellular network has been under consideration for several years and the third Generation Partnership Project, 3GPP, deals with this topic in the framework of self-organizing networks (SON). In a self-organizing network, cell outage detection and compensation is part of a self-healing process as described in 3GPP TS 32.541.
M. Amirijoo, L. Jorguseski et al. describe in an FP7 SOCRATES project in <<Cell Outage Management in LTE Networks>> the difficulties that arise in detecting sleeping cell, when cells show symptoms of malfunctioning without explicitly declaring alarm. Furthermore, there is no uniform cell outage compensation solution to all cells, deployments and traffic scenarios. Different network operators may have different optimization goals and network self-healing policies. The traffic and deployment particulars of the cells and their neighbours all influence the potential of cell outage detection and compensation.
Up to now, research has been focusing on the theory of cell outage detection and compensation. The used methods balance between the accuracy and trigger time of detection and they are typically based on statistics. On the other hand, the suggested compensation methods involve multivariate optimization, which also involves a trade-off between convergence, accuracy and time. A cell outage can be the end stage of a gradual performance degradation, but it rather happens all of a sudden. When a cell outage occurs, the network management has to take prompt remedy actions, there is no time to start a relatively slow optimization process, which may not even converge to full compensation.
In view of the above said, a need exists to further improve a cell outage detection and to speed up the outage compensation.